320 research outputs found

    The M_BH-M_star relation of obscured AGNs at high redshift

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    We report the detection of broad Halpha emission in three X-ray selected obscured AGNs at z=1-2. By exploiting the Halpha width and the intrinsic X-ray luminosity, we estimate their black hole masses, which are in the range 0.1-3x10^9 Msun. By means of multi-band photometric data, we measure the stellar mass of their host galaxy and, therefore, infer their M_BH/M_star ratio. These are the first obscured AGNs at high-z, selected based on their black hole accretion (i.e. on the basis of their X-ray luminosity), that can be located on the M_BH-M_star relation at high-z. All of these obscured high-z AGNs are fully consistent with the local M_BH-M_star relation. This result conflicts with those for other samples of AGNs in the same redshift range, whose M_BH/M_star ratio departs significantly from the value observed in local galaxies. We suggest that the obscured AGNs in our sample are in an advanced evolutionary stage, have already settled onto the local M_BH-M_star relation, and whose nuclear activity has been temporarily revived by recent galaxy interactions.Comment: 4 pages, 2 figures, accepted for publication in A&A Letters, slightly revised discussion on SMG

    Sistema de percepción de alta precisión para sistemas inteligentes de transporte

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    Robocity2030 7th Workshop. Móstoles. Spain. Oct, 2010. Visión en Robótica (2010).Este trabajo describe el sistema de percepción de alta precisión implementado sobre un autobús articulado para su conducción automática a través de un carril guía. Entre las infraestructuras de transporte más prometedoras de los sistemas de transporte automáticos, el bus articulado presenta un costo bajo relacionada con la cantidad de pasajeros que puede transportar, además del confort de los mismos relacionados con otros medios de transporte masivo. La plataforma experimental que se presenta en este trabajo consiste en un vehículo móvil y un circuito privado dentro de las instalaciones del CSIC. El sistema de percepción que se presenta en este trabajo está basado en dos escáneres láser 2D, donde la principal objetivo radica en la detección de un carril guía construido en el circuito, mediante un algoritmo híbrido eficiente de extracción de líneas, y la detección de obstáculos posibles sobre el recorrido del circuito.Este trabajo ha sido realizado en el marco del proyecto Robocity2030-II S2009/DPI-1559 subvencionado por la Dirección General de Investigación de la Consejería de Educación y Cultura de la Comunidad de Madrid e IMADE PIE/62/2008 (Comunidad de Madrid, ALDESA CONSTRUCCIONES SA, MAXIMASDE), y la Agencia Española de Cooperación Internacional para el Desarrollo (AECID) en el marco del proyecto FORTUNA D/026706/09. El Dr. Héctor Montes agradece el apoyo recibido de la Universidad Tecnológica de Panamá y del CSIC bajo el Programa JAE-Doc.Peer reviewe

    Reconfiguration of a climbing robot in an all-terrain hexapod robot

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    This work presents the reconfiguration from a previous climbing robot to an all-terrain robot for applications in outdoor environments. The original robot is a six-legged climbing robot for high payloads. This robot has used special electromagnetic feet in order to support itself on vertical ferromagnetic walls to carry out specific tasks. The reconfigured all-terrain hexapod robot will be able to perform different applications on the ground, for example, as inspection platform for humanitarian demining tasks. In this case, the reconfigured hexapod robot will load a scanning manipulator arm with a specific metal detector as end-effector. With the implementation of the scanning manipulator on the hexapod robot, several tasks about search and localisation of antipersonnel mines would be carried out. The robot legs have a SCARA configuration, which allows low energy consumption when the robot performs trajectories on a quasi-flat terrain.Peer reviewe

    Classification of Landsat 8 images in the Segura Hydrographic Demarcation

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    [EN] This work presents a cartography of land uses in the Segura Hydrographic Demarcation obtained by classifying 2017 Landsat 8 images. The classification was carried out using two classifiers: Maximum Likelihood (ML) and Random Forest (RF). Training areas were obtained from historical high resolution imagery until 2016. Prior to classification, a cross validation analysis of the training areas was carried out to determine which of them may have undergone a change of use between 2016 and 2017. The results obtained with ML and RF, both with the original set of training areas and with the one obtained eliminating the problem, are compared to determine the best option. In the case of ML, the results improve after eliminating the changing training areas, from 77.7% to 81.4%; however, with RF this improvement is not so important, going from 84.1% to 85.1%. Therefore, it can be concluded that, with both methods, the classification is more exact when the modified training areas are used and, although the results obtained are quite acceptable for both ML and RF, the latter performs a more accurate classification.[ES] En el presente trabajo se obtiene, a través de un proceso de clasificación digital de imágenes Landsat 8 de 2017, una cartografía de usos del suelo en la Demarcación Hidrográfica del Segura; la clasificación se ha llevado a cabo empleando dos clasificadores: Máxima Verosimilitud (MV) y Random Forest (RF). Puesto que las áreas de entrenamiento se obtienen de imágenes históricas de alta resolución hasta 2016, previamente a la clasificación, se hace un análisis de validación cruzada de las áreas de entrenamiento para determinar cuáles de ellas pueden haber sufrido un cambio de uso entre 2016 y 2017. Los resultados obtenidos con MV y con RF, tanto con el conjunto original de áreas como con el obtenido eliminando la problemática, se comparan para determinar cuál es la mejor opción. En el caso de MV mejoran notablemente los resultados cuando se realiza la depuración de las áreas de entrenamiento, pasando de un porcentaje de acierto del 81% al 84,9%; sin embargo, con RF esta mejora no es tan importante ya que se pasa del 84,1% al 85,1%. Por tanto, se puede concluir que, con ambos métodos la clasificación es más exacta cuando se emplean las áreas de entrenamiento depuradas y, aunque los resultados obtenidos son bastante aceptables tanto para MV como para RF, este último realiza una clasificación más exacta.Rodríguez-Valero, MI.; Alonso-Sarria, F. (2019). Classification of Landsat 8 images in the Segura Hydrographic DemarcationClasificación de imágenes Landsat-8 en la Demarcación Hidrográfica del Segura. Revista de Teledetección. (53):33-44. https://doi.org/10.4995/raet.2019.11016SWORD33445

    Identification of a non-host semiochemical from miniature pinscher, Canis lupus familiaris, that repels Rhipicephalus sanguineus sensu lato (Acari: Ixodidae)

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    It is already known that the beagle breed of domestic dogs produces semiochemicals capable of repelling the brown dog tick, Rhipicephalus sanguineus sensu lato (s.l.). With a view to discovering new non-host semiochemicals as tick repellents, we compared the semiochemicals produced by a putative tick-resistant breed of dog, miniature pinscher, with known tick-resistant (beagle) and tick-susceptible (English cocker spaniel) breeds. Two non-host compounds produced by beagles, i.e. 2-hexanone and benzaldehyde, were shown to be present in volatile samples collected from all three breeds. Furthermore, two compounds, 6-methyl-5-hepten-2-one and 1,2,4-trimethylbenzene, were found in higher amounts in volatile samples collected from miniature pinscher dogs. The mean amounts of benzaldehyde, 2- hexanone and 1,2,4-trimethylbenzene were similar for beagles and miniature pinschers and higher than the means observed for cocker spaniels, whereas the mean amount of 6-methyl-5-hepten-2-one produced by miniature pinschers was significantly higher than for the other breeds of dogs. In Petri-dish assays with adult R. sanguineus, 6-methyl-5- hepten-2-one was repellent for all observation periods evaluated for the two highest concentrations (0.100 and 0.200 mg.cm-2). Our results support our hypothesis that miniature pinschers are a tick-resistant dog breed and agree with previous observations of miniature pinschers being the breed least parasitized by ticks. Furthermore, the non-host semiochemical 6-methyl-5-hepten-2-one has potential to be developed for use as a repellent for the protection of susceptible dogs from R. sanguineus s.l. ticks

    Constraints on Recoil Leader Properties Estimated from X-ray Emissions in Aircraft-Triggered Discharges

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    During Airbus aircraft campaigns flying into thunderstorms in 2014–2016, X-rays were observed during two stages of aircraft-triggered lightning: nanosecond pulses of X-rays associated with negative leader steps and bursts of X-rays during recoil events. This work will focus on the observations of X-ray bursts associated with recoils. Recoils are observed as microsecond-fast changes in the local electric field, associated with large currents passing through the aircraft, and are found to sometimes be associated with bursts of X-rays. From over 200 aircraft-triggered lightning strikes, 54 recoil events were found to be associated with microsecond bursts of X-rays. The majority of the bursts consist of 1–3 X-ray pulses, with some bursts containing as many as 29 X-ray pulses. We compare the observed superposed X-ray spectrum with modeled spectra using a GEANT4 model of the detector and aircraft, to determine the source potential needed to accelerate the electrons that produce the observed X-rays. A model of the recoil leader was made to determine the gap distance and gap potential between the recoil leader and the aircraft. From the modeling, we determine a solution space for the gap and leader lengths where the gap length is constrained by the observed minimum and maximum times between the onset of the X-ray pulses and the onset of the current pulses detected at the aircraft (1 to 93 m). We also find two constraints from the fitting of the modeled spectra to the superposed spectrum, limiting the leader length to between 1 and ∼240 m.publishedVersio
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